An increasing number of organic materials are being employed as flavoring agents for modifying or improving the flavor and aroma of tobaccos, foodstuffs, beverages and other such consumer products.
The incorporation of flavorants in tobacco products is an important development in the tobacco industry due to the lowered aromaticity of the available tobacco and the increased preference of smokers for filter cigarettes and low delivery cigarettes.
It has been established that alkylpyrazines are natural components of tobacco smoke, and that they most probably are important contributors to tobacco smoke flavor [A. Baggett et al, J. Chromatog, 97, 79 (1974)]. Further, it has been disclosed in the patent literature that addition of alkylpyrazines to tobacco results in an improvement in the flavor of smoking compositions as perceived by a test panel.
British 1,244,068 describes a method for influencing the smoke flavor of tobacco or a tobacco mixture which consists of treating the tobacco with a pyrazine derivative of the following chemical structure: ##STR2## in which each R is independently a hydrogen atom, an aliphatic radical, an alicyclic radical or an aromatic hydrocarbon radical such radicals having up to 9 carbon atoms, or R is a heterocycli radical containing 4 to 9 carbon atoms.
U.S. Pat. No. 3,402,051 describes a process for imparting a popcorn-like flavor and aroma to tobacco and foodstuffs by the incorporation of a 2-acetylpyrazine derivative therein.
Other patents which disclose the addition of various pyridine and pyrazine compounds to tobacco and foodstuffs as a means of providing flavor or flavor enhancement include U.S. Pat. Nos. 3,684,809; 3,705,158; 3,716,543; 3,754,934; 3,764,349; 3,767,426; and 3,881,025.
U.S. Pat. No. 3,914,227 discloses pyridyl and pyrazyl ketones and their use in altering the organoleptic properties of tobacco and foodstuffs, and U.S. Pat. No. 4,166,869 discloses acylpyrimidines useful as flavorants for the same type of applications.
Alkylpyridines have also been found to be useful tobacco additives. As an example, U.S. Pat. No. 3,625,224 describes the use of methylpyridines, ethylpyridines and various dialkylpyridines as tobacco additives. U.S. Pat. No. 3,381,691 discloses 2-methyl-5-isopropylpyridine as a tobacco additive.
It is characteristic of pyridine, pyrazine, pyrimidine and other heterocyclic derivatives employed as tobacco flavorants in the prior art, as illustrated by the above described technical literature, that the respective heterocyclic derivatives have the disadvantage of both high volatility and low odor threshold. Both of these properties significantly restrict the extent that these heterocyclic derivatives can be utilized as flavorants in tobacco compositions. A quantity of a pyrazine or pyridine derivative in a tobacco composition sufficient to have a noticeable effect in low delivery cigarettes causes a marked pack aroma.
In a similar manner, the use of carboxylic acid flavorants for tobacco products has received acceptance because of the desirable aroma and flavor characteristics which they impart to the smoke (J. C. Leffingwell, H. J. Young, and E. Bernasek, "Tobacco Flavoring for Smoking Products," R. J. Reynolds Tobacco Company, Winston-Salem, 1972). Specifically, acetic acid is commonly used as an ingredient of a Latakia tobacco flavoring formulation (J. Merory, "Food Flavorings," AVI Publishing Company, Incorporated, Westport, Connecticut, page 420, 1968). Isovaleric acid and 3-methylvaleric acid are major ingredients in a Turkish tobacco flavor formulation (R. H. Stedman and C. D. Stills, U.S. Pat. No. 3,180,340). Desirable flavors have been imparted to cigarette smoke by the addition of 4-ketoacids to tobacco (W. A. Rohde, U.S. Pat. No. 3,313,307).
Numerous methods of adding flavorants to tobacco smoke are known. However, none of the known methods has been found to be completely satisfactory, particularly when the flavorant is a low molecular weight carboxylic acid. Specifically, some of these acids are highly volatile and possess objectionably strong odors that render them difficult to use in bulk amounts required for manufacturing purposes. In addition, some of the volatile acids may impart an undesirable pack aroma.
In an attempt to alleviate some of these problems, carboxylic acids have been incorporated in tobacco as part of a compound (i.e., an organic acid release agent) in such form that upon burning of the tobacco the compound will liberate one or more organic acids imparting a selected and desired flavor and aroma to the smoke. While considerably more satisfactory than earlier attempts, even this technique has evidenced certain drawbacks.
U.S. Pat. No. 2,766,145 through U.S. Pat. No. 2,766,150 describe a variety of methods for treating tobacco with compounds that release carboxylic acids on pyrolysis. The U.S. Pat. No. 2,766,145 patent describes esters of monohydric and polyhydric compounds. The hydroxy compounds may be aliphatic or aromatic in nature.
The U.S. Pat. No. 2,766,146 describes esters of a sugar acid selected from aldonic acids and uronic acids. U.S. Pat. No. 2,766,150 describes nonvolatile synthetic polymers or condensation products preferably those related to polyvinyl alcohol and vinyl alcohol-type condensation products. On pyrolysis, the carboxylic acid is liberated to flavor the smoke. These polymers have a distinct disadvantage in that they generally have high molecular weights and are more difficult to solubilize for application on tobacco.
Other references which disclose tobacco flavorant compositions that release carboxylic acids on pyrolysis include U.S. Pat. No. 4,036,237 and U.S. Pat. No. 4,171,702.
There remains a need for smoking compositions with enhanced flavor and aroma that do not exhibit the various disadvantages of prior art smoking compositions which contain flavorant additives of the types described above.
Accordingly, it is a main object of this invention to provide tobacco and non-tobacco smoking compositions which have incorporated therein a flavorant additive which is characterized by low volatility and low pack aroma.
It is another object of this invention to provide smoking compositions of tobacco and non-tobacco materials, and blends thereof, containing a heterocyclic-hydroxy-substituted carboxylate flavorant additive, which smoking compositions are adapted to impart flavor and aroma to the mainstream and sidestream smoke under smoking conditions.
It is a further object of this invention to provide novel heterocyclic-hydroxy-substituted carboxylate compounds which can be subjected to pyrolysis conditions to release heterocyclic and carboxylic constituents which can enhance the flavor and aroma of smoking compositions and foodstuffs.
Other objects and advantages of the present invention shall become apparent from the accompanying description and examples.